Manufacturing method of press-molded article and press molding apparatus

ABSTRACT

A manufacturing method of press-molded article of the present invention comprises a step of placing a member to be pressed in a press molding apparatus and a step of pressing a flat plate portion of the member to be pressed by bringing a first press portion and a second press portion closer to each other. A first opposing surface and a second opposing surface, while facing to each other, keep in contact with the flat plate portion during pressing. In the press step, a thick part is formed on the flat plate portion by allowing a part of a material of the flat plate portion to flow, in a press direction, into a thickened portion-forming section formed on the first opposing surface. The second opposing surface is moved to the press direction as the flat plate portion is pressed by the first press portion and the second press portion.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.15/298,395 filed Oct. 20, 2016, which claims priority to and the benefitof Japanese Patent Application No. 2015-225995 filed Nov. 18, 2015, theentire contents of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION Field of the Invention

The present invention relates to a manufacturing method of press-moldedarticle and a press molding apparatus.

Description of the Related Art

There has been conventionally known a technique of manufacturing a metalplate used in a vehicle skeleton part of automobile and the like bypress molding. In the above uses, there are growing demands on not onlya metal plate having a fixed thickness, but also a metal plate having athickness difference by partially forming a thickened portion. Amanufacturing apparatus and method of the metal plate having such athickened portion by press molding are disclosed in the following patentdocuments, JP 2014-166645 A, JP 2007-14978 A, and JP 2008-296252 A.

In the press molding apparatuses disclosed in JP 2014-166645 A and JP2007-14978 A, both main surfaces of a metal plate are held by a top andbottom pair of dies and the metal plate is pressed in a directionparallel to the main surfaces while maintaining this condition. By thisoperation, a material of the metal plate flows into a concave portionprovided on a part of a holding surface of the die to form a thickenedportion. Further, in JP 2008-296252 A, a metal plate folded into aU-shape has an extension portion in one part thereof in a longitudinaldirection and a thickened portion is formed on the part in thelongitudinal direction when the extension portion is pressed.

In the press molding apparatuses disclosed in the above patentdocuments, JP 2014-166645 A and JP 2007-14978 A, the both main surfacesof the metal plate are held by the top and bottom pair of dies and themetal plate is pressed in a direction parallel to the main surfacesunder a condition where positions of the dies are fixed. In thisconfiguration, friction force generated by sliding between the dies andthe metal plate increases and pressing force, which is required forpressing, increases excessively. On the other hand, in the press moldingapparatus disclosed in the above patent document, JP 2008-296252 A,there is a large gap between the dies and the metal plate, therebysometimes causing folding of the metal plate during pressing. When thefolding occurs to the metal plate, a flow direction of the material ofthe metal plate becomes out of control, thus making it difficult to formthe thickened portion having a desired shape.

The present invention has been made in view of the foregoing problems,and an object thereof is to provide a manufacturing method ofpress-molded article and a press molding apparatus, capable of forming athickened portion having a desired shape while reducing pressing force.

SUMMARY OF THE INVENTION

(1) A manufacturing method of press-molded article according to oneembodiment of the present invention is a method for manufacturing apress-molded article by molding a member to be pressed including a flatplate portion. The method comprises:

a step of placing the member to be pressed in a press molding apparatusin a manner such that a first main surface of the flat plate portion isopposed to a first opposing surface and a second main surface of theflat plate portion, directing opposite to the first main surface, isopposed to a second opposing surface; and

a step of pressing the flat plate portion by bringing a first pressportion opposing to a first end portion of the flat plate portion and asecond press portion opposing to a second end portion of the flat plateportion, the second end portion being located on an opposite side of thefirst end portion, closer to each other. The first opposing surface andthe second opposing surface, while facing to each other, keep in contactwith the flat plate portion during pressing. In the press step, a thickportion is formed on the flat plate portion by allowing a part of amaterial of the flat plate portion to flow, in a press direction, into athickened portion-forming section formed on at least one of the firstopposing surface and the second opposing surface, and at least one ofthe first opposing surface and the second opposing surface is moved tothe press direction as the flat plate portion is pressed by the firstpress portion and the second press portion.

In the above method, when the flat plate portion is pressed by bringingthe first press portion and the second press portion closer to eachother, the opposing surface opposing to the main surface of the flatplate portion is moved to the press direction. Thus, as compared to aconventional case where the press is performed while the opposingsurface is fixed without moving, friction force generated by slidingbetween the main surface of the flat plate portion and the opposingsurface can be further reduced. As a result, necessary pressing forcecan be further reduced.

Further, in the above method, the thick portion, of which a thickness isincreased, can be formed on the flat plate portion by pressing the flatplate portion using the first press portion and the second press portionand allowing a part of the material of the flat plate portion to flow,in the press direction, into the thickened portion-forming section.During this process, the first opposing surface and the second opposingsurface, while facing to each other, keep in contact with the flat plateportion during pressing, thus enabling to prevent an occurrence offolding to the flat plate portion during pressing and suppress thenon-uniformity of a flow direction of the material. As a result, thematerial of the flat plate portion can be reliably flown into thethickened portion-forming section to form the thickened portion having adesired shape.

The term “first end portion and second end portion” herein refers toboth ends of the flat plate portion in the press direction.

(2) In the above manufacturing method of press-molded article, in thestep of placing the member to be pressed, the flat plate portion may beplaced between a die provided with the first press portion and the firstopposing surface and a die provided with the second press portion andthe second opposing surface.

Having such a configuration can further simplify an apparatus structurein comparison with a case where the first press portion and the firstopposing surface are provided in separate members and the second pressportion and the second opposing surface are provided in separatemembers.

(3) In the above manufacturing method of press-molded article, the dieprovided with the first opposing surface may include a first dividedportion and a second divided portion formed separately from the firstdivided portion. The first press portion may be formed in the firstdivided portion and the second press portion may be formed in the seconddivided portion. In the press step, the first divided portion may bemoved to the press direction of the first press portion as the flatplate portion is pressed by the first press portion, and the seconddivided portion is moved to the press direction of the second pressportion as the flat plate portion is pressed by the second pressportion.

In this configuration, the first and second end portions of the flatplate portion can be pressed by the first and second press portions,respectively, by bringing the first divided portion and the seconddivided portion closer to each other. Thus, the first opposing surfacescan be moved to the press directions of the first and second pressportions accordingly and friction force generated between the mainsurface of the flat plate portion and the opposing surfaces can befurther effectively reduced. As a result, pressing force can be furtherreduced.

(4) In the above manufacturing method of press-molded article, the firstdivided portion and the second divided portion may have a comb-teethshape so as to mesh with each other. In the press step, the firstdivided portion and the second divided portion may come close to eachother in such a manner that the both comb teeth mesh with each other.

In this configuration, the flat plate portion can be press-molded in astate of being further stably supported.

(5) In the above manufacturing method of press-molded article, in thestep of placing the member to be pressed, the member to be pressed maybe placed so as to arrange the first main surface and the second mainsurface of the flat plate portion along a perpendicular direction.

Having such a configuration can reduce an installation area of the pressmolding apparatus, thereby saving a space, in comparison with a casewhere the first main surface and the second main surface are arrangedalong a horizontal direction.

(6) In the above manufacturing method of press-molded article, in thestep of placing the member to be pressed, positions of the first mainsurface and the second main surface may be maintained along theperpendicular direction by supporting the flat plate portion using atemporarily supporting member.

Having such a configuration can stably support the flat plate portion toprevent it from falling when the first main surface and the second mainsurface of the flat plate portion are vertically arranged along theperpendicular direction.

(7) In the above manufacturing method of press-molded article, in thepress step, pressing force may be applied to the material of the flatplate portion flowing into the thickened portion-forming section.

Having such a configuration can further effectively prevent anoccurrence of folding to the flat plate portion in the process offorming a thick part by allowing the material of the flat plate portionto flow into the thickened portion-forming section.

(8) In the above manufacturing method of press-molded article, themember to be pressed may be molded by a hot press.

The above method enables to press the flat plate portion without causingfolding as described above, thus a flow direction of the material can befurther reliably controlled even when the hot press is used.

(9) A press molding apparatus according to another embodiment of thepresent invention is a press molding apparatus for molding a member tobe pressed including a flat plate portion. The press molding apparatuscomprises: a first press portion opposing to a first end portion of theflat plate portion; a second press portion opposing to a second endportion of the flat plate portion, the second end portion being locatedon an opposite side of the first end portion; a first opposing surfaceopposing to a first main surface of the flat plate portion; a secondopposing surface opposing to a second main surface of the flat plateportion, the second main surface directing opposite to the first mainsurface; and a driving section for bringing the first press portion andthe second press portion closer to each other to press the flat plateportion. A thickened portion-forming section is formed on at least oneof the first opposing surface and the second opposing surface forforming a thick part on the flat plate portion by allowing a part of amaterial of the flat plate portion to flow into the thickenedportion-forming section. The first opposing surface and the secondopposing surface are, while facing to each other, configured to keep incontact with the flat plate portion during pressing. At least one of thefirst opposing surface and the second opposing surface is configured tomove to a press direction as the flat plate portion is pressed by thefirst press portion and the second press portion.

In the above press molding apparatus, the opposing surface opposing tothe main surface of the flat plate portion can be moved to the pressdirection as the flat plate portion is pressed by bringing the firstpress portion and the second press portion closer to each other. Thus,as compared to a conventional case where the press is performed whilethe opposing surface is fixed without moving, friction force generatedby sliding between the main surface of the flat plate portion and theopposing surface can be further reduced. As a result, necessary pressingforce can be further reduced.

Further, in the above press molding apparatus, the thickened portion, ofwhich a thickness is increased, can be formed on the flat plate portionby pressing the flat plate portion using the first press portion and thesecond press portion and allowing a part of the material of the flatplate portion to flow, in the press direction, into the thickenedportion-forming section. During this process, the first opposing surfaceand the second opposing surface, while facing to each other, keep incontact with the flat plate portion during pressing, thus the flat plateportion can be prevented from being folded during pressing and a flowdirection of the material can be suppressed from becoming non-uniform.As a result, the material of the flat plate portion can be reliablyflown into the thickened portion-forming section to form the thickenedportion having a desired shape.

(10) In the above press molding apparatus, the first press portion andthe first opposing surface may be provided in a same die. The secondpress portion and the second opposing surface may be provided in a samedie.

Having such a configuration can further simplify a structure of pressmolding apparatus in comparison with a case where the first pressportion and the first opposing surface are provided in separate membersand the second press portion and the second opposing surface areprovided in separate members.

(11) In the above press molding apparatus, the die provided with thefirst opposing surface may include a first divided portion and a seconddivided portion formed separately from the first divided portion. Thefirst press portion may be formed in the first divided portion and thesecond press portion may be formed in the second divided portion.

In this configuration, the first and second end portions of the flatplate portion can be pressed by the first and second press portions,respectively, by bringing the first divided portion and the seconddivided portion closer to each other. Thus, the first opposing surfacescan be moved to the press directions of the first and second pressportions accordingly and friction force generated between the mainsurface of the flat plate portion and the opposing surfaces can befurther effectively reduced. As a result, pressing force can be furtherreduced.

(12) In the above press molding apparatus, the first divided portion andthe second divided portion may have a comb-teeth shape so as to meshwith each other.

In this configuration, the flat plate portion can be press-molded in astate of being further stably supported.

(13) In the above press molding apparatus, the first opposing surfaceand the second opposing surface may be arranged along a perpendiculardirection.

Having such a configuration can reduce an installation area of the pressmolding apparatus, thereby saving a space, in comparison with a casewhere the first and second opposing surfaces are arranged along ahorizontal direction.

(14) The above press molding apparatus may comprise a temporarilysupporting member for supporting the flat plate portion to maintainpositions of the first main surface and the second main surface alongthe perpendicular direction.

Having such a configuration can stably support the flat plate portion toprevent it from falling even when the first main surface and the secondmain surface are vertically arranged along the perpendicular direction.

(15) The above press molding apparatus may comprise a back-pressureapplicator for applying pressure force to the material of flat plateportion flowing into the thickened portion-forming section.

Having such a configuration can further effectively prevent anoccurrence of folding to the flat plate portion in the process offorming the thick part by allowing the material of the flat plateportion to flow into the thickened portion-forming section.

The above press molding apparatus enables to press the flat plateportion without causing folding as described above, thus a flowdirection of the material can be further reliably controlled even when ahot press is used.

The present invention can provide the manufacturing method ofpress-molded article and the press molding apparatus, capable of formingthe thickened portion having a desired shape while reducing pressingforce.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view of a configuration of a press moldingapparatus according to a first embodiment of the present invention.

FIG. 2 is an enlarged view around a thickened portion-forming section ofthe above press molding apparatus.

FIG. 3 is a flowchart showing procedures of a manufacturing method ofpress-molded article according to the first embodiment of the presentinvention.

FIG. 4 is a diagram showing how a member to be pressed is heated by anelectric furnace.

FIG. 5 is a diagram showing how a flat plate portion is pressed to forma thickened portion.

FIG. 6 is a schematic view of a press-molded article.

FIG. 7 is a graph showing measured results of a molding load and apressing load.

FIG. 8 is a schematic view of a configuration of a press moldingapparatus according to a first modification of the above firstembodiment.

FIG. 9 is a diagram showing how a flat plate portion is pressed to forma thickened portion in the above first modification.

FIG. 10 is a schematic view of a configuration of a press moldingapparatus according to a second embodiment of the present invention.

FIG. 11 is a diagram showing how a flat plate portion is pressed in theabove second embodiment.

FIG. 12 is a diagram showing how the flat plate portion is pressed toform a thickened portion in the above second embodiment.

FIG. 13 is a schematic view of a configuration of a press moldingapparatus according to a first modification of the above secondembodiment.

FIG. 14 is a schematic view of the configuration of the press moldingapparatus according to the first modification of the above secondembodiment.

FIG. 15 is a schematic view of a configuration of a press moldingapparatus according to a second modification of the above secondembodiment.

FIG. 16 is a diagram showing how a flat plate portion is pressed to forma thickened portion in the second modification of the above secondembodiment.

FIG. 17A and FIG. 17B are schematic views of a configuration of a pressmolding apparatus according to a third embodiment of the presentinvention.

FIG. 18A and FIG. 18B are diagrams showing how a flat plate portion isarranged between dies in the above third embodiment.

FIG. 19A and FIG. 19B are diagrams showing how the flat plate portion ispressed to form a thickened portion in the above third embodiment.

FIG. 20A and FIG. 20B are schematic views of a configuration of a pressmolding apparatus according to a first modification of the above thirdembodiment.

FIG. 21A and FIG. 21B are diagrams showing how a flat plate portion isarranged between dies in the first modification of the above thirdembodiment.

FIG. 22A and FIG. 22B are diagrams showing how the flat plate portion ispressed to form a thickened portion in the first modification of theabove third embodiment.

FIG. 23A and FIG. 23B are schematic views of a configuration of a pressmolding apparatus according to a second modification of the above thirdembodiment.

FIG. 24A and FIG. 24B are diagrams showing how a flat plate portion ispressed to form a thickened portion in the second modification of theabove third embodiment.

FIG. 25A and FIG. 25B are schematic views of a configuration of a pressmolding apparatus according to a third modification of the above thirdembodiment.

FIG. 26A and FIG. 26B are diagrams showing how a flat plate portion ispressed to form a thickened portion in the third modification of theabove third embodiment.

FIG. 27A and FIG. 27B are schematic views of a configuration of a pressmolding apparatus according to a fourth modification of the above thirdembodiment.

FIG. 28A and FIG. 28B are diagrams showing how a flat plate portion ispressed to form a thickened portion in the fourth modification of theabove third embodiment.

FIG. 29 is a diagram showing a configuration of divided portions inanother modification of the above third embodiment.

FIG. 30 is a schematic view of a configuration of a press moldingapparatus according to a fourth embodiment of the present invention.

FIG. 31 is a diagram showing how a flat plate portion is pressed in theabove fourth embodiment.

FIG. 32 is a diagram showing how the flat plate portion is pressed toform a thickened portion in the above fourth embodiment.

FIG. 33 is a schematic view of a configuration of a press moldingapparatus according to a first modification of the above fourthembodiment.

FIG. 34 is a diagram showing how a flat plate portion is pressed in thefirst modification of the above fourth embodiment.

FIG. 35 is a diagram showing how the flat plate portion is pressed toform a thickened portion in the first modification of the above fourthembodiment.

FIG. 36 is a schematic view of a configuration of a press moldingapparatus according to another embodiment of the present invention.

FIG. 37 is a diagrammatic illustration for describing partial electricheating.

FIG. 38 is a diagrammatic illustration for describing press-molding of aflat plate portion subjected to the partial electric heating.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, embodiments of the present invention will be described indetail with reference to the drawings.

First Embodiment

[Configuration of Press Molding Apparatus]

First of all, a configuration of a press molding apparatus 1 accordingto a first embodiment of the present invention will be described bymainly referring to FIG. 1.

The press molding apparatus 1 is an apparatus for press-molding a memberto be pressed including a flat plate portion 10, such as a metal platehaving a fixed thickness, so as to partially form a thick part(thickened portion) on the flat plate portion 10. The press moldingapparatus 1 comprises a first die 11, a second die 12, a supportingmember 13, a press member 18, and a drive section 18B.

The member to be pressed is, for example, a metal plate made of amaterial, such as hard steel, soft steel, or aluminum. In an exampleshown in the drawing, the whole member to be pressed is constituted bythe flat plate portion 10.

It is noted that, in the present invention, the whole member to bepressed is not necessary to be constituted by the flat plate portion 10,and the member to be pressed may include the flat plate portion 10 atone part. The flat plate portion 10 comprises a first main surface 10C,a second main surface 10D, directing opposite to the first main surface10C, a first end portion 10A, and a second end portion 10B, which islocated on an opposite side of the first end portion 10A.

The first die 11 is fixed on a mount surface 13A of the supportingmember 13 by a fixing member such as a bolt B. The first die 11comprises an opposing portion 11C opposing to the flat plate portion 10,and a guide portion 11D for guiding a movement of the second die 12,arranged with an interval from the opposing portion 11C.

The opposing portion 11C comprises a first opposing surface 11B opposingto the first main surface 10C and a first press portion 11A opposing tothe first end portion 10A. In this configuration, the first pressportion 11A and the first opposing surface 11B are provided in the samefirst die 11. The first opposing surface 11B is connected to an uppersurface 11F at its upper end and vertically arranged along aperpendicular direction (parallel to perpendicular direction). The firstpress portion 11A is connected to a lower end of the first opposingsurface 11B and formed flatly along a horizontal direction (parallel tohorizontal direction).

A thickened portion-forming section 15 as a concave groove is formednear a center of the first opposing surface 11B. The thickenedportion-forming section 15 is provided to form a thickened portion, ofwhich a thickness is increased, on the flat plate portion 10 by allowinga part of a material of the flat plate portion 10 in a press directionduring press-molding. The thickened portion-forming section 15 issurrounded by a pair of horizontal sidewall surfaces, stretchinghorizontally, and a bottom wall surface connecting between inner sideend portions of the pair of sidewall surfaces, and recessed in adirection away from the flat plate portion 10. The thickenedportion-forming section 15 is formed on one part of the first opposingsurface 11B in the press direction.

It is noted that a shape of the thickened portion-forming section 15 isnot limited thereto and can be appropriately changed according to ashape of the thickened portion formed on the flat plate portion 10. Forexample, the shape may have a semi-circular cross section, a triangularcross section, and the like. Further, the first opposing surface 11B mayinclude a plurality of the thickened portion-forming sections 15.Further, the thickened portion-forming section 15 needs not be formed inthe center.

A plurality of guide rollers 17 are arranged on an inner surface of theguide portion 11D. The second die 12 has its lower end part between theguide portion 11D and the opposing portion 11C and moves to theperpendicular direction according to contraction of a spring 16. Duringthis process, the guide rollers 17 comes into contact with a sidesurface of the second die 12, thereby guiding a movement of the seconddie 12 in the perpendicular direction.

The second die 12 is connected to an upper end of the spring 16 at itslower surface and has its lower end part between the opposing portion11C and the guide portion 11D. Before the press-molding is started (FIG.1), an upper surface 12C of the second die 12 is located higher than anupper surface 11F of the first die 11.

The second die 12 comprises a second opposing surface 12B opposing tothe second main surface 10D and a second press portion 12A opposing tothe second end portion 10B. In this configuration, the second pressportion 12A and the second opposing surface 12B are provided in the samesecond die 12. The second opposing surface 12B is connected to thesecond press portion 12A at its upper end and vertically arranged alongthe perpendicular direction (parallel to perpendicular direction). Thesecond press portion 12A is formed flatly along the horizontal direction(parallel to horizontal direction).

The second die 12 is arranged in a manner such that the second opposingsurface 12B is opposed to the first opposing surface 11B in thehorizontal direction across the flat plate portion 10 and the secondpress portion 12A is opposed to the first press portion 11A in theperpendicular direction across the flat plate portion 10. In thisconfiguration, the flat plate portion 10 can be arranged between thefirst die 11 and the second die 12.

In FIG. 2, a thickness of the flat plate portion 10 is represented byT1, a distance between the first and second opposing surfaces 11B and12B is represented by D1, and a distance between a bottom wall surface15A of the thickened portion-forming section 15 and the second opposingsurface 12B is represented by D2. In the press molding apparatus 1, thedistance D1 is adjusted according to the thickness T1, so that a ratioof distance D1 (mm)/thickness T1 (mm) becomes 1.1 or lower. For example,when the flat plate portion 10 having the thickness T1 of 1.4 mm ispressed, the distance D1 is adjusted to 1.6 mm. Further, the distance D2is adjusted to 2.2 mm.

As shown in FIG. 2, before the pressing is started (i.e., before theflat plate portion 10 is pressed by the first and second press portions11A and 12A), a gap between the flat plate portion 10, and the firstopposing surface 11B and second opposing surface 12B may be formedunless the gap causes folding during pressing. In another words, thefirst opposing surface 11B and the second opposing surface 12B areopposed to each other with the distance D1 sufficient to avoid thefolding of the flat plate portion 10 during pressing. The term “foldingof the flat plate portion 10” herein refers to a condition where theflat plate portion 10 is folded to such a degree that a flow of thematerial of the flat plate portion 10 caused by pressing is disturbed,and does not include a minute swell of the flat plate portion 10 causedduring pressing unless it affects the flow of the material.

Then, during pressing, the first opposing surface 11B and the secondopposing surface 12B, while facing to each other, keep in contact withthe flat plate portion 10. However, the flat plate portion 10 needs notalways contact with the first opposing surface 11B or the secondopposing surface 12B during pressing. Further, the whole flat plateportion 10 needs not contact with the first opposing surface 11B or thesecond opposing surface 12B.

As shown in FIG. 1, the supporting member 13 is a metallic member havinga rectangular parallelepiped shape and comprises the flat mount surface13A on which a lower surface of the first die 11 is placed. The mountsurface 13A of the supporting member 13 is laterally arranged along thehorizontal direction and fixed on the first die 11 by a fixing membersuch as the bolt B.

A press member 18 is a member that presses the upper surface 12C of thesecond die 12 to move the second die 12 downward in the perpendiculardirection. The press member 18 having a press surface 18A is moveddownward in the perpendicular direction by operating a driving section18B. Then, the upper surface 12C of the second die 12 is pressed by thepress surface 18A, so that the second die 12 can move downward in theperpendicular direction.

The driving section 18B is arranged in contact with an upper surface 18Cof the press member 18. The driving section 18B comprises, for example,a hydraulic or electric piston and presses the upper surface 18C to movethe press member 18 downward in the perpendicular direction.

In the above press molding apparatus 1, first of all, the press member18 is lowered by operating the driving section 18B, so that the presssurface 18A is brought into contact with the upper surface 12C of thesecond die 12. The press member 18 is further lowered to move the seconddie 12 downward in the perpendicular direction while maintaining thisstate, so that the second press portion 12A is brought closer to thefirst press portion 11A. Then, the flat plate portion 10 is pressed bythe first press portion 11A and the second press portion 12A from theboth end portions 10A and 10B in a direction parallel to the mainsurfaces 10C and 10D (FIG. 5). By this operation, a part of the materialof the flat plate 10 is flown, in the press direction, into thethickened portion-forming section 15 to form the thickened portion.

In this configuration in the above press molding apparatus 1, the secondopposing surface 12B is moved to the press direction as the pressing isperformed by the first and second press portions 11A and 12A. That is,the second opposing surface 12B is slid toward the same direction as thepress direction of the flat plate portion 10. Thus, friction forcegenerated by sliding between the second main surface 10D and the secondopposing surface 12B can be reduced and pressing force required formolding the flat plate portion 10 can be reduced.

[Manufacturing Method of Press-Molded Article]

Next, a manufacturing method of press-molded article using the abovepress molding apparatus 1, according to the present embodiment, will bedescribed along a flowchart shown in FIG. 3. First of all, a member tobe pressed is prepared in a step S10. In the step S10, the member to bepressed including the flat plate portion 10, such as a metal platehaving a fixed thickness, is prepared and heated with a predeterminedtemperature by an electric furnace F (FIG. 4). By this operation, thewhole flat plate portion 10 becomes softened. In the present embodiment,a press-molded article is manufactured by a hot press, in which thewhole flat plate portion 10 is heated to be softened and then molded. Itis noted that the present invention is not limited to the case where thehot press is performed, and may adopt a cold working without performingthe step S10.

Next, the member to be pressed is placed in a step S20. In the step S20,the flat plate portion 10 softened in the above step S10 is placedbetween the first die 11 and the second die 12 (FIG. 1). Morespecifically, the flat plate portion 10 is placed in such a manner thatthe first main surface 10C is opposed to the first opposing surface 11Balong the perpendicular direction and the second main surface 10D isopposed to the second opposing surface 12B along the perpendiculardirection. During this process, the first opposing surface 11B and thesecond opposing surface 12B, while facing to each other, keep in contactwith the flat plate portion 10 during pressing to prevent an occurrenceof folding to the flat plate portion 10 in a following press step S30.

Next, the member to be pressed is pressed in a step S30. In the stepS30, first of all, the press member 18 is lowered by operating thedriving section 18B, so that the press surface 18A is brought intocontact with the upper surface 12C of the second die 12. Then, the pressmember 18 is further lowered to press the upper surface 12C of thesecond die 12, so that the second die 12 is moved downward and thesecond press portion 12A is brought closer to the first press portion11A. By this operation, the flat plate portion 10 is pressed by thefirst press portion 11A and the second press portion 12A from the bothend portions 10A and 10B in the direction parallel to the main surfaces10C and 10D. Then, a part of the material of the flat plate portion 10is flown into the thickened portion-forming section 15 in the pressdirection (arrows in FIG. 5) to form the thickened portion, of which athickness is increased, on the flat plate portion 10. Subsequently, theoperation of the driving section 18B is stopped at the time when thepress surface 18A comes into contact with the upper surface 11F of thefirst die 11.

In the step S30, the second opposing surface 12B is moved (slid) towardthe press direction as the flat plate portion 10 is pressed by the firstpress portion 11A and the second press portion 12A. That is, the secondopposing surface 12B is moved to the same direction as the pressdirection of the flat plate portion 10. Thus, friction force generatedby sliding between the second main surface 10D and the second opposingsurface 12B can be reduced during pressing and the flat plate portion 10can be molded with less pressing force.

Further, the first and second opposing surfaces 11B and 12B, whilefacing to each other, keep in contact with the flat plate portion 10during pressing. This can prevent the flat plate portion 10 from beingfolded during pressing, thereby suppressing the non-uniformity of theflow direction of the material. Thus, the material of the flat plateportion 10 can be reliably flown into the thickened portion-formingsection 15 from the both end portions 10A and 10B. As a result, thethickened portion can be formed in a desired shape in accordance withthe shape of the thickened portion-forming section 15.

Finally, the press-molded article is taken out in a step S40. In thestep S40, the press member 18 is moved up by operating the drivingsection 18B after completing the press-molding of the flat plate portion10 in the step S30. Then, a press-molded article 100 having a thickenedportion 100A formed thereon (FIG. 6) is taken out. Through the abovesteps S10 to S40, the manufacturing method of press-molded articleaccording to the present embodiment is completed.

Advantageous Effects

Next, representative configurations and advantageous effects of theabove press molding apparatus 1 will be described.

The above press molding apparatus 1 comprises the first press portion11A, the second press portion 12A, the first opposing surface 11B, thesecond opposing surface 12B, and the driving section 18B that brings thefirst press portion 11A and the second press portion 12A closer to eachother. The first opposing surface 11B includes the thickenedportion-forming section 15 for forming the thick part on the flat plateportion 10. The first opposing surface 11B and the second opposingsurface 12B, while facing to each other, keep in contact with the flatplate portion 10 during pressing. The thickened portion-forming section15 is configured in such a manner that the part of the material of theflat plate portion 10 is flown, in the press direction, into thethickened portion-forming section 15 as the flat plate portion 10 ispressed by the first press portion 11A and the second press portion 12A.The second opposing surface 12B is configured to move to the pressdirection as the flat plate portion 10 is pressed by the first pressportion 11A and the second press portion 12A.

In the above press molding apparatus 1, the second opposing surface 12Bcan be moved to the press direction as the first press portion 11A andthe second press portion 12A come closer to each other to press the flatplate portion 10. Thus, as compared to a conventional case where thepressing is performed while the opposing surface is fixed withoutmoving, friction force generated by sliding between the second mainsurface 10D and the second opposing surface 12B can be further reduced.As a result, necessary pressing force can be further reduced.

A graph in FIG. 7 shows an effect of load reduction achieved in thepresent embodiment, in which the pressing is performed while moving theopposing surface. In the graph in FIG. 7, columns 1 and 2 show values ofa molding load and a pressing load in a case where the pressing isperformed without moving the opposing surface and a case where thepressing is performed while moving the opposing surface, respectively.The term “molding load” refers to a load required for press-molding theflat plate portion 10, while the term “pressing load” refers to a loadrequired for fixing a clearance between the dies. As is evident from thegraph, the molding load is significantly reduced (reduced up to aboutone-tenth) when the pressing is performed while moving the opposingsurface as compared to the case where the pressing is performed withoutmoving the opposing surface.

Further, in the above press molding apparatus 1, the thickened portion100A, of which a thickness is increased, can be formed on the flat plateportion 10 by pressing the flat plate portion 10 by the first pressportion 11A and the second press portion 12A and allowing the part ofthe material of the flat plate portion 10 to flow into the thickenedportion-forming section 15 in the press direction. During this process,the first opposing surface 11B and the second opposing surface 12B,while facing to each other, keep in contact with the flat plate portion10 during pressing. This can prevent the non-uniformity of the flowdirection of the material caused by folding generated in the flat plateportion 10 during pressing. That is, it becomes possible to control theflow of the material. Thus, the material of the flat plate portion 10can be reliably flown into the thickened portion-forming section 15,thereby enabling to form the thickened portion 100A having a desiredshape.

In the above press molding apparatus 1, the first press portion 11A andthe first opposing surface 11B are provided in the same first die 11,and the second press portion 12A and the second opposing surface 12B areprovided in the same second die 12. This can further simplify astructure of the press molding apparatus 1 in comparison with a casewhere the first press portion 11A and the first opposing surface 11B areprovided in separate members and the second press portion 12A and thesecond opposing surface 12B are provided in separate members.

In the above press molding apparatus 1, the first opposing surface 11Band the second opposing surface 12B are arranged along the perpendiculardirection. This can reduce an installation area of the press moldingapparatus 1, thereby saving a space, in comparison with a case where thefirst opposing surface 11B and the second opposing surface 12B arearranged along the horizontal direction.

[First Modification]

Next, a press molding apparatus 1A according to a first modification ofthe above first embodiment will be described with reference to FIG. 8and FIG. 9. In the press molding apparatus 1A according to the firstmodification, the opposing portion 11C of the first die 11 and the guideportion 11D are provided separately from each other. Further, the pressmember 18 comprises a main body portion 18D, which has the upper surface18C in contact with the driving section 18B, and a press portion 18Efixed on a lower surface 18G of the main body portion 18D. The pressportion 18E is made from a shape in which a press portion main body 18H,fixed on the lower surface 18G by a fixing member such as a bolt B, isconnected to a first supporting portion 18F and a second supportingportion 18I. The press portion 18E is formed in an upside down U-shapein a cross sectional view.

The press portion main body 18H comprises a press surface 18J thatpresses the upper surface 12C of the second die 12. The first supportingportion 18F and the second supporting portion 18I extend downward in theperpendicular direction from both end portions of the press portion mainbody 18H in the horizontal direction.

A first inner surface 18K is formed inside the first supporting portion18F and a second inner surface 18L is formed inside the secondsupporting portion 18I. A horizontal distance between the first innersurface 18K and the second inner surface 18L is made slightly largerthan that between side surfaces of the first die 11 (opposing portion11C) and the second die 12. In this configuration, when the press member18 is lowered to press the flat plate portion 10 as shown in FIG. 9, thefirst die 11 (opposing portion 11C) and the second die 12 can be placedbetween the first and second supporting portions 18F and 18I. This canfurther reliably prevent displacement of the first and second dies 11and 12 during pressing.

Second Embodiment

Next, a press molding apparatus 2 and a manufacturing method ofpress-molded article according to a second embodiment of the presentinvention will be described with reference to FIG. 10 to FIG. 12. It isnoted that only the parts in which the second embodiment differs fromthe above first embodiment will be described in detail.

[Configuration of Press Molding Apparatus]

The press molding apparatus 2 comprises a first die 21, a second die 22,a supporting member 26, and a driving section 28B. The first die 21 isformed in an approximately rectangular parallelepiped shape andcomprises a first opposing surface 21B opposing to the first mainsurface 10C, a first side surface 21C directing opposite to the firstopposing surface 21B, and a first press portion 21A opposing to thefirst end portion 10A. In this configuration, the first press portion21A and the first opposing surface 21B are provided in the same firstdie 21. The first side surface 21C of the first die 21 is fixed on afixed surface 26A of the supporting member 26 by a fixing member such asa bolt B.

The first opposing surface 21B is connected to an upper surface 21F atits upper end and arranged along the perpendicular direction. The firstpress portion 21A is connected to a lower end of the first opposingsurface 21B so as to form an acute angle at the point of intersection. Athickened portion-forming section 25 as a concave groove is formed neara center of the first opposing surface 21B and used for forming athickened portion by allowing a part of the material of the flat plateportion 10 to flow into the thickened portion-forming section 25 duringpressing.

The second die 22 comprises a second die main body 28 and a die fixingmember 29 connected to an upper surface of the second die main body 28.The second die main body 28 is formed in a rectangular parallelepipedshape, having a size capable of being inserted into a die space 26Bformed in the supporting member 26. The second die main body 28comprises a second opposing surface 22B opposing to the second mainsurface 10D, a second side surface 22C directing opposite to the secondopposing surface 22B, and a second press portion 22A opposing to thesecond end portion 10B. In this configuration, the second press portion22A and the second opposing surface 22B are provided in the same seconddie 22. The second opposing surface 22B is connected to the second pressportion 22A at its upper end and arranged along the perpendiculardirection. The second press portion 22A intersects with the secondopposing surface 22B so as to form an acute angle. The die fixing member29 has the approximately same width as the supporting member 26 andfixed to the upper surface of the second die main body 28 by the bolt B.

The second die main body 28 is inserted into the die space 26B (FIG.11), so that the second opposing surface 22B is arranged to be opposedto the first opposing surface 21B across the flat plate portion 10 inthe horizontal direction and the second press portion 22A is arranged tobe opposed to the first press portion 21A across the flat plate portion10 in the perpendicular direction. Thus, the flat plate portion 10 canbe placed between the first die 21 and the second die 22. In thisconfiguration, the first opposing surface 21B and the second opposingsurface 22B, while facing to each other, keep in contact with the flatplate portion 10 during pressing. Further, the second side surface 22 Ccomes into contact with guide rollers 27, thereby guiding a movement ofthe second die main body 28 in the perpendicular direction.

The supporting member 26 is a metallic member and includes the die space26B having a concave shape, to which the second die main body 28 isinserted. The supporting member 26 comprises the fixed surface 26A towhich the first die 21 is fixed, a bottom surface 26C opposing to alower surface 22D of the second die main body 28, and a guide surface26D on which a plurality of the guide rollers 27 are arranged.

The driving section 28B is arranged in contact with an upper surface 29Aof the die fixing member 29. The driving section 28B comprises, as inthe above first embodiment, a hydraulic or electric piston and moves thesecond die 22 downward in the perpendicular direction by pressing theupper surface 29A.

[Manufacturing Method of Press-Molded Article]

Next, explanation is given to a manufacturing method of press-moldedarticle using the above press molding apparatus 2. First of all, amember to be pressed including the flat plate portion 10 is softened byheating to be prepared (FIG. 3: S10). Next, the flat plate portion 10 isplaced in the first die 21 while the second die 22 is positioned abovethe first die 21 (FIG. 10). Then, the second die 22 is lowered byoperating the driving section 28B, so that the second die main body 28is inserted into the die space 26B, and the second press portion 22A isbrought into contact with the second end portion 10B (FIG. 11). By thisoperation, the member to be pressed is placed in a manner such that thefirst main surface 10C is opposed to the first opposing surface 21B andthe second main surface 10D is opposed to the second opposing surface22B (FIG. 3: S20). During this process, the first and second mainsurfaces 10C and 10D are arranged along the perpendicular direction.Further, the first opposing surface 21B and the second opposing surface22B, while facing to each other, keep in contact with the flat plateportion 10 during pressing.

Next, the second die 22 is further lowered by operating the drivingsection 28B, so that the second press portion 22A is brought closer tothe first press portion 21A. By this operation, the flat plate portion10 is pressed by the first press portion 21A and the second pressportion 22A in a direction parallel to the main surfaces 10C and 10D,and a part of the material of the flat plate portion 10 is flown intothe thickened portion-forming section 25 (FIG. 12). By this operation,the thickened portion, of which a thickness is increased, is formed onone part of the flat plate portion 10 (FIG. 3: S30). During thisprocess, as in the above first embodiment, the second opposing surface22B is moved toward the press direction as the flat plate portion 10 ispressed by the first press portion 21A and the second press portion 22A.Then, after the press of the flat plate portion 10 is completed, thesecond die 22 is moved up by operating the driving section 28B and apress-molded article is taken out (FIG. 3: S40).

In the above second embodiment, as in the above first embodiment, thesecond opposing surface 22B is moved toward the press direction as theflat plate portion 10 is pressed by the first press portion 21A and thesecond press portion 22A in the perpendicular direction. Thus, frictionforce generated by sliding between the second main surface 10D and thesecond opposing surface 22B can be reduced during pressing and the flatplate portion 10 can be molded with less pressing force. Further, thefirst opposing surface 21B and the second opposing surface 22B, whilefacing to each other, keep in contact with the flat plate portion 10during pressing. This can prevent the non-uniformity of the flowdirection of the material of the flat plate portion 10 caused by foldinggenerated during pressing, thus the material of the flat plate portion10 can be reliably flown into the thickened portion-forming section 25.Further, in the configuration of the above second embodiment, the firstside surface 21C of the first die 21 is fixed to the supporting member26 and the second die 22 (second die main body 28) is inserted into thedie space 26B of the supporting member 26, thus displacement of thefirst and second dies 21 and 22 can be further reliably prevented duringpressing.

[First Modification]

Next, a press molding apparatus 2A according to a first modification ofthe above second embodiment will be described with reference to FIG. 13and FIG. 14. The press molding apparatus 2A according to the firstmodification further comprises a temporarily supporting member 26E,which prevents the flat plate portion 10 from falling.

The press molding apparatus 2A comprises a pair of the temporarilysupporting members 26E each having a thin plate shape. As shown in FIG.14, each temporarily supporting member 26E is provided outside of aninsertion region of the second die 22. Each temporarily supportingmember 26E is formed in an elongate shape extending from a lower end toan upper end, and the upper end is bent in a direction away from theflat plate portion 10 while the lower end is attached to the supportingmember 26 by a fixture 26F. The temporarily supporting members 26Econtact with both end parts of the second main surface 10D of the flatplate portion 10, thereby supporting the flat plate portion 10 so as tomaintain the first main surface 10C and the second main surface 10Dalong the perpendicular direction.

In the above press molding apparatus 2A, first of all, the flat plateportion 10 is placed between the first die 21 and the temporarilysupporting members 26E. During this process, the flat plate portion 10is supported by the temporarily supporting members 26E and thusmaintained in a vertical condition where the first and second mainsurfaces 10C and 10D are arranged along the perpendicular direction.Subsequently, the second die 22 (second die main body 28) is insertedinto the die space 26B and the flat plate portion 10 is arranged betweenthe first die 21 and the second die 22. In this manner, before the flatplate portion 10 is arranged between the first die 21 and the second die22, the temporarily supporting members 26E can stably support the flatplate portion 10 and prevent it from falling.

[Second Modification]

Next, a press molding apparatus 2B according to a second modification ofthe above second embodiment will be described with reference to FIG. 15and FIG. 16. The press molding apparatus 2B according to the secondmodification comprises a back-pressure applicator 25E that appliespressure force to the material of the flat plate portion 10 flowing intoa thickened portion-forming section 25A.

The thickened portion-forming section 25A is formed as a hole thatpenetrates in the horizontal direction at a substantially center of thefirst die 21. A through hole 26G is formed in the supporting member 26and communicates with the thickened portion-forming section 25A.

The back-pressure applicator 25E comprises a pad portion 25B, an elasticmember 25C, and a supporting portion 25D. The pad portion 25B is formedin a convex shape and arranged inside the thickened portion-formingsection 25A. The elastic member 25C is constituted by a spring thatenergizes the pad portion 25B and arranged inside the through hole 26G.The elastic member 25C is arranged between the pad portion 25B and thesupporting portion 25D. Both ends of the elastic member 25C may or maynot be connected to the pad portion 25B and the supporting portion 25D.The supporting portion 25D is integrally fixed to the supporting member26.

When the flat plate portion 10 is pressed by the first press portion 21Aand the second press portion 22A, the material of the flat plate portion10 flows into the thickened portion-forming section 25A while pushingthe pad portion 25B and thereby causing compression of the elasticmember 25C. During this process, restoring force of the elastic member25C is imparted, via the pad portion 25B, to the material flowing intothe thickened portion-forming section 25A. That is, the material of theflat plate portion 10 flows into the thickened portion-forming section25A while the pressure force is applied to the material by theback-pressure applicator 25E. In this manner, an occurrence of foldingto the flat plate portion 10 can be further effectively prevented in theprocess of flowing the material into the thickened portion-formingsection 25A by pressing the flat plate portion 10.

Third Embodiment

Next, a press molding apparatus 3 and a manufacturing method ofpress-molded article according to a third embodiment of the presentinvention will be described with reference to FIG. 17A to FIG. 19B. Itis noted that only the parts in which the third embodiment differs fromthe above first embodiment will be described in detail.

[Configuration of Press Molding Apparatus]

The press molding apparatus 3 comprises a first die 33, a second die 34arranged above the first die 33, a supporting member 39 on which thefirst die 33 is placed, a press member 38, and a driving section 38B.The first die 33 is constituted of a first divided portion 31 and asecond divided portion 32 formed separately from the first dividedportion 31. The first divided portion 31 and the second divided portion32 are arranged to be opposed to each other in the horizontal direction.

The first divided portion 31 comprises a first portion 31D to bepressed, which is pressed by the press member 38, a first press portion31E for pressing the flat plate portion 10, and a first mount portion31F on which the flat plate portion 10 is placed. A first surface 31C tobe pressed, formed on an upper part of the first portion 31D to bepressed, is pressed by a first press surface 38F. A first press portion31A, formed on a side part of the first press portion 31E, is opposed tothe first end portion 10A of the flat plate portion 10. A first opposingsurface 31B, formed on an upper part of the first mount portion 31F, isopposed to the first main surface 10C of the flat plate portion 10.

The second divided portion 32 has a symmetrical shape to the firstdivided portion 31. That is, the second divided portion 32 comprises asecond portion 32D to be pressed, which is pressed by the press member38, a second press portion 32E for pressing the flat plate portion 10,and a second mount portion 32F on which the flat plate portion 10 isplaced. A second surface 32C to be pressed, formed on an upper part ofthe second portion 32D to be pressed, is pressed by a second presssurface 38G. A second press portion 32A, formed on a side part of thesecond press portion 32E, is opposed to the second end portion 10B ofthe flat plate portion 10. A first opposing surface 32B, formed on anupper part of the second mount portion 32F, is opposed to the first mainsurface 10C of the flat plate portion 10. Further, the first opposingsurfaces 31B and 32B are laterally arranged along the horizontaldirection (parallel to horizontal direction).

The first and second mount portions 31F and 32F have a comb-teeth shapeso as to mesh with each other. Specifically, as shown by arrows in FIG.17B, the comb teeth of the first mount portion 31F are inserted intogaps between the comb teeth of the second mount portion 32F, and viceversa, as the first and second mount portions 31F and 32 are broughtcloser to each other.

The second die 34 is formed in an approximately rectangularparallelepiped shape and comprises a second opposing surface 34Bopposing to the second main surface 10D of the flat plate portion 10.The second opposing surface 34B is laterally arranged along thehorizontal direction (parallel to horizontal direction). A thickenedportion-forming section 35 is formed as a concave groove near a centerof the second opposing surface 34B, so that a thickened portion, ofwhich a thickness is increased, can be formed on the flat plate portion10 by allowing a part of the material of the flat plate portion 10 toflow into the thickened portion-forming section 35 during pressing.Further, when the flat plate portion 10 is arranged between the firstand second dies 33 and 34 (FIG. 18A), the first opposing surfaces 31Band 32B, and the second opposing surface 34B, while facing to eachother, keep in contact with the flat plate portion 10 during pressing.

The supporting member 39 is a member made of metal, formed in arectangular parallelepiped shape, and used for mounting the first die33. A plurality of guide rollers 37 are arranged on an upper surface ofthe supporting member 39, and allows the first and second dividedportions 31 and 32 to slide in the horizontal direction.

The press member 38 presses the first and second divided portions 31 and32, thereby sliding them in the horizontal direction. The press member38 comprises a main body portion 38A in contact with the driving section38H and a press portion 38B fixed on a lower surface of the main bodyportion 38A. The press portion 38B is made from a shape in which a pressportion main body 38C, fixed on the lower surface of the main bodyportion 38A by the bolt B, is connected to a first extension portion 38Dand a second extension portion 38E. A cross section of the press portion38B cut with a plane including a width direction (right/left directionin FIG. 17B) of the flat plate portion 10 and the perpendiculardirection has an upside down U-shape. A lower surface of the pressportion main body 38C is connected to an upper surface of the second die34 by a plurality of (two) springs. The first press surface 38F forpressing the first divided portion 31 is formed at a tip of the firstextension portion 38D, while the second press surface 38G for pressingthe second divided portion 32 is formed at a tip of the second extensionportion 38E.

The driving section 38H is arranged in contact with the upper surface ofthe press member 38 (main body portion 38A). The driving section 38Hcomprises, as in the above first embodiment, a hydraulic or electricpiston, and moves the press member 38 downward in the perpendiculardirection by pressing.

[Manufacturing Method of Press-Molded Article]

Next, explanation is given to a manufacturing method of press-moldedarticle using the above press molding apparatus 3. First of all, amember to be pressed including the flat plate portion 10 is softened byheating to be prepared (FIG. 3: S10).

Next, the flat plate portion 10 is placed on the first and seconddivided portions 31 and 32 with the first main surface 10C turneddownward (FIG. 17A), while the second die 34 is positioned above them(FIG. 17A). Next, the press member 38 is lowered by operating thedriving section 38H, so that the second die 34 fixed to the press member38 is also lowered. By this operation, as shown in FIG. 18A, the flatplate portion 10 is placed in a manner such that the first main surface10C is opposed to the first opposing surfaces 31B and 32B, and thesecond main surface 10D is opposed to the second opposing surface 34B(FIG. 3: S20). During this process, the first opposing surfaces 31B and32B, and the second opposing surface 34B, while facing to each other,keep in contact with the flat plate portion 10 during pressing.

Next, the press member 38 is further lowered by operating the drivingsection 38H, so that the first and second press surfaces 38F and 38G arebrought into contact with the first and second surfaces 31C and 32C tobe pressed, respectively (FIG. 19A). When the press member 38 is furtherlowered while maintaining this state, the first press surface 38F, whilesliding on the first surface 31C to be pressed, makes the first dividedportion 31 slide to a side of the second divided portion 32, and thesecond press surface 38G, while sliding on the second surface 32C to bepressed, makes the second divided portion 32 slide to a side of thefirst divided portion 31. By this operation, the first and seconddivided portions 31 and 32 approach each other so as to cause tips ofthe comb teeth of one divided portion to abut gaps between the combteeth of the other divided portion (FIG. 19B). In this manner, when thefirst and second divided portions 31 and 32 approach each other, thefirst and second press portions 31A and 32 a also come close to eachother and the flat plate portion 10 is pressed from the both sides ofthe end portions 10A and 10B in the horizontal direction. During thisprocess, a part of the material of the flat plate portion 10 is flowninto the thickened portion-forming section 35 in the press direction,thereby forming a thickened portion, of which a thickness is increased,on the flat plate portion 10.

In the press step, the first divided portion 31 moves to the pressdirection of the first press portion 31A (direction from left to rightin drawing) as the first press portion 31A presses the flat plateportion 10. Further, the second divided portion 32 moves to the pressdirection of the second press portion 32A (direction from right to leftin drawing) as the second press portion 32A presses the flat plateportion 10. Thus, the first opposing surface 31B is moved to the pressdirection of the first press portion 31A as the flat plate portion 10 isbeing pressed, and the second opposing surface 32B is moved to the pressdirection of the second press portion 32A as the flat plate portion 10is being pressed. Then, after the press of the flat plate portion 10 iscompleted, the press member 38 and the second die 34 are moved up byoperating the driving section 38H and a press-molded article is takenout (FIG. 3: S40).

In the above third embodiment, the first die 33 is divided into thefirst divided portion 31 and the second divided portion 32. By bringingthem closer to each other, the first and second end portions 10A and 10Bof the flat plate portion 10 can be pressed by the first and secondpress portions 31A and 32A, respectively. In this configuration, thefirst opposing surface 31B and the first opposing surface 32B can bemoved in the opposite directions to each other according to the pressdirections of the first and second press portions 31A and 32A. As aresult, friction force generated between the first main surface 10C, andthe first opposing surfaces 31B and 32B can be further effectivelyreduced and pressing force can be further reduced. Further, the firstand second divided portions 31 and 32 are formed in the comb-teeth shapeso as to mesh with each other, thus the flat plate portion 10 can bepress-molded while being stably supported.

[First Modification]

Next, a first modification of the above third embodiment will bedescribed with reference to FIG. 20A to FIG. 22B. In a press moldingapparatus 3A according to the first modification, a plurality of (two)thickened portion-forming sections 35 are formed at intervals from eachother on the second opposing surface 34B. In this configuration, bypressing the flat plate portion 10 using the first and second pressportions 31A and 32A, the material of the flat plate portion 10 can beflown into each of the plurality of the thickened portion-formingsections 35 (FIG. 22A), thereby enabling to manufacture a press-moldedarticle having a more complicated shape.

It is noted that a shape and size of each thickened portion-formingsection 35 may be the same or different from each other. Further theintervals between the thickened portion-forming sections 35 can beappropriately designed according to a shape of the press-molded article.

[Second Modification]

Next, a second modification of the above third embodiment will bedescribed with reference to FIG. 23A and FIG. 24B. A press moldingapparatus 3B according to the second modification comprises, asdescribed in the second modification of the above second embodiment, aback-pressure applicator 35D that applies pressure force to the materialof the flat plate portion 10 flowing into a thickened portion-formingsection 35A.

The thickened portion-forming section 35A having a hole shape is formednear a center of the second opposing surface 34B. The back-pressureapplicator 35D comprises a pad portion 35B and an elastic member 35C.The pad portion 35B is formed in a convex shape and arranged inside thethickened portion-forming section 35A. The elastic member 35C isconstituted by a spring that energizes the pad portion 35B, and one endof the elastic member 35C is connected to the pad portion 35B and theother end is connected to a hole wall surface of the second die 34.

As shown in FIG. 24A, when the flat plate portion 10 is pressed by thefirst and second press portions 31A and 32A, the material of the flatplate portion 10 presses the pad portion 35B while flowing into thethickened portion-forming section 35A. During this process, restoringforce of the elastic member 35C is imparted to the material flowing intothe thickened portion-forming section 35A via the pad portion 35B. Thatis, the material of the flat plate portion 10 flows into the thickenedportion-forming section 35A, while pressure force is applied to thematerial by the back-pressure applicator 35D. In this manner, anoccurrence of folding to the flat plate portion 10 can be furthereffectively prevented in the process of flowing the material of the flatplate portion 10 into the thickened portion-forming section 35A.

(Third Modification)

Next, a third modification of the above third embodiment will bedescribed with reference to FIG. 25A and FIG. 26B. In a press moldingapparatus 3C according to the third modification, the first dividedportion 31 and the second divided portion 32 are connected to each otherby a spring 33A.

The first divided portion 31 comprises a first mount portion 31G of aquadrangular shape in a plan view (FIG. 25B) and a first protrusion 31Hprojected from a side surface of the first mount portion 31G. A firstopposing surface 31B is formed on an upper part of the first mountportion 31G. The first protrusion 31H is provided to the first mountportion 31G with a difference in height, so that an upper surface of thefirst protrusion 31H is located lower than the first opposing surface31B (FIG. 25A).

The second divided portion 32 comprises a second mount portion 32G of aquadrangular shape, of which an area is smaller than that of the firstmount portion 31G, in a plan view (FIG. 25B). A first opposing surface32B is formed on an upper part of the second mount portion 32G. Furtherthe second divided portion 32 is provided with a hollow portion 32H, inwhich the first protrusion 31H can be inserted. That is, the hollowportion 32H is formed to be larger than the first protrusion 31H. Theflat plate portion 10 is placed on the first opposing surfaces 31B and32B so as to cross over the first and second divided portions 31 and 32(FIG. 25A).

In this configuration, the first and second divided portions 31 and 32are connected to each other by the spring 33A, thus a positionalrelation between the first and second divided portions 31 and 32 can befurther reliably maintained. Further, in this configuration, the firstprotrusion 31H can be inserted into the hollow portion 32H, therebyenabling to guide the movement of the first and second divided portions31 and 32 in horizontal direction during pressing.

(Fourth Modification)

Next, a fourth modification of the above third embodiment will bedescribed with reference to FIG. 27A and FIG. 28B. In a press moldingapparatus 3D according to the fourth modification, the first dividedportion 31 comprises a first mount portion 31I of an approximatelyright-angled triangle shape in a plan view (FIG. 27B). The firstopposing surface 31B is formed on an upper part of the first mountportion 31I. Further, the second divided portion 32 comprises a secondmount portion 32I of an approximately right-angled triangle shape,symmetric to that of the first mount portion 31I, in a plan view (FIG.27B). The first opposing surface 32B is formed on an upper part of thesecond mount portion 32I. By bringing the first and second mountportions 31I and 32I closer to each other, slopes 31J and 32J of theright-angled triangles come in contact with each other to form a mountsurface having a quadrangular shape in a plan view (FIG. 28B). Also inthis modification, as is the case using the comb-teeth shape describedin the above third embodiment, the flat plate portion 10 can be pressedwhile being stably supported.

It is noted that the shapes of the first and second divided portions 31and 32 are not limited to the comb-teeth shape and the right-angledtriangle shape as described above. Specifically, various shapes of thefirst and second divided portions 31 and 32 can be adopted as long assuch a shape allows the first and second divided portions 31 and 32 tooverlap each other, at least partially, in the press direction at a timepoint when the thickened portion is formed on the flat plate portion 10by pressing.

Further, when the comb-teeth shape is adopted, both comb teeth need notbe completely inserted to each other at the time of completion of thepressing, as shown in FIG. 19B. For example, as shown in FIG. 29, in aregion R, to which a pair of meshing portions are externally contactingat the time of completion of the pressing, there may be gaps S of sizenot causing an inflow of the material or folding during press-molding.

Fourth Embodiment

Next, a press molding apparatus 4 and a manufacturing method ofpress-molded article according to a fourth embodiment of the presentinvention will be described with reference to FIG. 30 to FIG. 32. It isnoted that only the parts in which the fourth embodiment differs fromthe above first embodiment will be described in detail.

[Configuration of Press Molding Apparatus]

The press molding apparatus 4 comprises a first die 41, a second die 42,a die opening prevention portion 43, a press member 48, and a drivingsection 48B.

The first die 41 comprises a first portion 41D to be pressed, which ispressed by the press member 48, a first press portion 41E for pressingthe flat plate portion 10, and a first mount portion 41F, on which theflat plate portion 10 is placed. A first surface 41C to be pressed,formed on an upper part of the first portion 41D to be pressed, ispressed by a first press surface 48F. Further, the first portion 41D tobe pressed is provided at each end located at a front side and a rearside of the drawing. A first press portion 41A, formed on a side part ofthe first press portion 41E, is opposed to the first end portion 10A ofthe flat plate portion 10. A first opposing surface 41B, formed on anupper part of the first mount portion 41F, is opposed to the first mainsurface 10C of the flat plate portion 10. In this manner, the firstpress portion 41A and the first opposing surface 41B are provided in thesame first die 41. The first opposing surface 41B is laterally arrangedalong the horizontal direction, and the first press portion 41A isconnected to an end part of the first opposing surface 41B so as to makean acute angle with the first opposing surface 41B. Further, a thickenedportion-forming section 45 as a concave groove is formed on the firstopposing surface 41B and used for forming a thick part on the flat plateportion 10 by allowing a part of the material of the flat plate portion10 to flow into the thickened portion-forming section 45 duringpressing.

The second die 42, arranged above the first die 41, has a structureapproximately symmetrical to the first die 41. That is, the second die42 comprises a second portion 42D to be pressed, which is pressed by thepress member 48, a second press portion 42E for pressing the flat plateportion 10, and a second opposing portion 42F opposing to the flat plateportion 10. A second surface 42C to be pressed, formed on the secondportion 42D to be pressed, is pressed by a second press surface 48G.Further, the second portion 42D to be pressed is provided at each endlocated at a front side and a rear side of the drawing. A second pressportion 42A, formed on a side part of the second press portion 42E, isopposed to the second end portion 10B of the flat plate portion 10. Asecond opposing surface 42B, formed on a lower part of the secondopposing portion 42F, is opposed to the second main surface 10D of theflat plate portion 10. In this manner, the second press portion 42A andthe second opposing surface 42B are provided in the same second die 42.The second opposing surface 42B is laterally arranged along thehorizontal direction, and the second press portion 42A is connected toan end part of the second opposing surface 42B so as to make an acuteangle with the second opposing surface 42B.

The first opposing surface 41B and the second opposing surface 42B,while facing to each other, keep in contact with the flat plate portion10 during pressing. Further, a plurality of guide rollers 47 arearranged on a lower part of the second die 42, so that the second die 42can slide on the first die 41 in the horizontal direction.

The die opening prevention portion 43 is a member that prevents dieopening of the first die 41 and the second die 42 and is formed arectangular shape enclosing the first die 41 and the second die 42. Thedie opening prevention portion 43 comprises a part positioned on anupper side of the second die 42 and a part positioned on a lower side ofthe first die 41, and prevents the die opening of the first die 41 andthe second die 42 by vertically clamping them. Further, the die openingprevention portion 43 comprises an inside upper surface 43A and aninside lower surface 43B, which are provided with a plurality of upperguide rollers 47A and a plurality of lower guide rollers 47B,respectively. An upper surface 41G and a lower surface 41H of the firstdie 41 are brought into contact with the upper guide rollers 47A and thelower guide rollers 47B, respectively, thereby enabling to slide thefirst die 41 in the horizontal direction. Further, an upper surface 42Gand the guide rollers 47 of the second die 42 are brought into contactwith the upper guide rollers 47A and the first die 41, respectively,thereby enabling to slide the second die 42 in the horizontal directionin a similar manner.

The press member 48 presses the first and second dies 41 and 42, therebysliding them in the horizontal direction. The press member 48 comprisesa main body portion 48A in contact with a driving section 48H and apress portion 48B fixed to a lower surface of the main body portion 48A.The press portion 48B is made from a shape in which a press portion mainbody 48C, fixed on the lower surface of the main body portion 48A by thebolt B, is connected to a first extension portion 48D and a secondextension portion 48E. The press portion 48B is formed in an upside downU-shape in a cross sectional view. The first press surface 48F forpressing the first die 41 is formed at a tip of the first extensionportion 48D, while the second press surface 48G for pressing the seconddie 42 is formed at a tip of the second extension portion 48E. Further,both the first and second extension portions 48D and 48E are provided ateach end located at a front side and a rear side of the drawing.

The driving section 48H is arranged in contact with an upper surface ofthe press member 48 (main body portion 48A). The driving section 48Hcomprises, as in the above first embodiment, a hydraulic or electricpiston and moves the press member 48 downward in the perpendiculardirection by pressing.

[Manufacturing Method of Press-Molded Article]

Next, explanation is given to a manufacturing method of press-moldedarticle using the above press molding apparatus 4. First of all, amember to be pressed including the flat plate portion 10 is softened byheating to be prepared (FIG. 3: S10). Next, the flat plate portion 10 isplaced between the first die 41 and the second die 42. By thisoperation, as shown in FIG. 30, the member to be pressed is placed in amanner such that the first main surface 10C is opposed to the firstopposing surface 41B and the second main surface 10D is opposed to thesecond opposing surface 42B (FIG. 3: S20). During this process, thefirst opposing surface 41B and the second opposing surface 42B, whilefacing to each other, keep in contact with the flat plate portion 10during pressing.

Next, the press member 48 is lowered by operating the driving section48H, so that the first and second press surfaces 48F and 48G are broughtinto contact with the first and second surfaces 41C and 42C to bepressed, respectively (FIG. 31). When the press member 48 is furtherlowered while maintaining this state, the first press surface 48F, whilesliding on the first surface 41C to be pressed, makes the first die 41slide in the horizontal direction, and the second press surface 48G,while sliding on the second surface 42C to be pressed, makes the seconddie 42 slide in the horizontal direction. By this operation, the firstand second press portions 41A and 42A approach each other and the flatplate portion 10 is pressed from the both sides of the end portions 10Aand 10B in the horizontal direction. During this process, a part of thematerial of the flat plate portion 10 is flown into the thickenedportion-forming section 45 in the press direction, thereby enabling toform a thickened portion, of which a thickness is increased, on the flatplate portion 10 (FIG. 3: S30).

In the press step, the first opposing surface 41B is moved to the pressdirection as the flat plate portion 10 is pressed by the first pressportion 41A and the second opposing surface 42B is moved to the pressdirection as the flat plate portion 10 is pressed by the second pressportion 42A. That is, both the first and second opposing surfaces 41Band 42B are moved to the press directions as the flat plate portion 10is being pressed. In this manner, both friction force generated bysliding between the first main surface 10C and the first opposingsurface 41B and friction force generated by sliding between the secondmain surface 10D and the second opposing surface 42B can be reduced.Thus, pressing force required for molding the flat plate portion 10 canbe further reduced. Then, after the press of the flat plate portion 10is completed, the press member 48 is moved up by operating the drivingsection 48H and a press-molded article is taken out (FIG. 3: S40).

(First Modification)

Next, a first modification of the above fourth embodiment will bedescribed with reference to FIG. 33 to FIG. 35. As shown in FIG. 33, ina press molding apparatus 4A according to the first modification, thethickened portion-forming section 45 is formed on the second opposingsurface 42B, instead of the first opposing surface 41B. In thisconfiguration, as shown in FIG. 34 and FIG. 35, a press-molded articlehaving a thickened portion formed on the second main surface 10D sidecan be manufactured by pressing the flat plate portion 10 with the firstand second press portions 41A and 42A and allowing the material of theflat plate portion 10 to flow into the thickened portion-forming section45. Further, when the thickened portions are formed both on the firstmain surface 10C and the second main surface 10D, the thickenedportion-forming sections 45 may be formed both on the first opposingsurface 41B and the second opposing surface 42B.

Other Embodiments

Finally, other embodiments of the present invention will be described.The present invention can be applied not only to a member to be pressed,in which the whole member to be pressed is constituted with a singleflat plate portion, as described above, but also to a member to bepressed including the flat plate portion in one part thereof. Forexample, as shown in FIG. 36, the present invention can be applied to amember 10E to be pressed of a bent shape, having a plurality of (two)flat plate portions 10F.

More specifically, a press molding apparatus 7 comprises an upper die 71including first and second upper dies 71A and 71B and a lower die 72including first and second lower dies 72A and 72B. The member 10E to bepressed is placed between the upper die 71 and the lower die 72. A firstpress portion 71C opposing to the first end portion 10A of the flatplate portion 10F is formed on the first upper die 71A, and a firstopposing surface 71D opposing to the first main surface 10C of the flatplate portion 10F is formed on the second upper die 71B. Further, asecond opposing surface 72D opposing to the second main surface 10D ofthe flat plate portion 10F is formed on the first lower die 72A, and asecond press portion 72C opposing to the second end portion 10B of theflat plate portion 10F is formed on the second lower die 72B.

As shown by arrows in FIG. 36, by lowering the first upper die 71A, theflat plate portion 10F is pressed by the first press portion 71C and thesecond press portion 72C in the direction parallel to the main surfaces10C and 10D, and a material of the flat plate portion 10F is flown intoa thickened portion-forming section 75 to form a thickened portion.During this process, when the first lower die 72A is pressed by thefirst upper die 71A and lowered, the second opposing surface 72D ismoved to the press direction. Thus, friction force generated by slidingbetween the second main surface 10D and the second opposing surface 72Dcan be reduced and, as in the cases for the above first to fourthembodiments, pressing force required for molding the flat plate portion10F can be reduced.

Further, the present invention is not limited to the case where thewhole flat plate portion 10 is heated by the electric furnace F (FIG.4). As shown in FIG. 37, a plurality of electrodes 101 may be arrangedat intervals from each other on the main surface of the flat plateportion 10 and a temperature rising portion 102 by heating is partiallyformed on the flat plate portion 10 by supplying electric current to theplurality of electrodes 101 (partial electrical heating). Then, as shownin FIG. 38, a thickened portion may be formed by pressing the flat plateportion 10 in a state of being arranged between dies 91 and 92 andallowing a material located at the temperature rising portion 102 byheating to flow into a thickened portion-forming section 95. In thismanner, remaining parts of the flat plate portion 10 other than thetemperature rising portion 102 by heating are kept at a low temperaturewithout being heated, thus such low-temperature parts are not softenedand retain high strength. This enables to further reduce a frictioncoefficient between the dies 91 and 92, and the flat plate portion 10during pressing. Further, instead of performing the partial electricalheating, the whole flat plate portion 10 may be subjected to electricalheating.

What is claimed is:
 1. A manufacturing method of press-molded article bymolding a member to be pressed including a flat plate portion, themethod comprising: a step of placing the member to be pressed in a pressmolding apparatus in a manner such that a first main surface of the flatplate portion is opposed to a first opposing surface and a second mainsurface of the flat plate portion, directing opposite to the first mainsurface, is opposed to a second opposing surface; and a step of pressingthe flat plate portion by bringing a first press portion opposing to afirst end portion of the flat plate portion and a second press portionopposing to a second end portion of the flat plate portion, the secondend portion being located on an opposite side of the first end portion,closer to each other, wherein: the first opposing surface and the secondopposing surface, while facing to each other, keep in contact with theflat plate portion during pressing; and in the press step: a thick partis formed on the flat plate portion by allowing a part of a material ofthe flat plate portion to flow, in a press direction, into a thickenedportion-forming section formed on at least one of the first opposingsurface and the second opposing surface; and at least one of the firstopposing surface and the second opposing surface is moved to the pressdirection as the flat plate portion is pressed by the first pressportion and the second press portion.
 2. The manufacturing method ofpress-molded article according to claim 1, wherein, in the step ofplacing the member to be pressed, the flat plate portion is placedbetween a die provided with the first press portion and the firstopposing surface and a die provided with the second press portion andthe second opposing surface.
 3. The manufacturing method of press-moldedarticle according to claim 1, wherein: the die provided with the firstopposing surface includes a first divided portion and a second dividedportion formed separately from the first divided portion; the firstpress portion is formed in the first divided portion; the second pressportion is formed in the second divided portion; and in the press step,the first divided portion is moved to the press direction of the firstpress portion as the flat plate portion is pressed by the first pressportion, and the second divided portion is moved to the press directionof the second press portion as the flat plate portion is pressed by thesecond press portion.
 4. The manufacturing method of press-moldedarticle according to claim 3, wherein: the first divided portion and thesecond divided portion have a comb-teeth shape so as to mesh with eachother; and in the press step, the first divided portion and the seconddivided portion come close to each other in such a manner that the bothcomb teeth mesh with each other.
 5. The manufacturing method ofpress-molded article according to claim 1, wherein, in the step ofplacing the member to be pressed, the member to be pressed is placed soas to arrange the first main surface and the second main surface of theflat plate portion along a perpendicular direction.
 6. The manufacturingmethod of press-molded article according to claim 5, wherein, in thestep of placing the member to be pressed, positions of the first mainsurface and the second main surface are maintained along theperpendicular direction by supporting the flat plate portion using atemporarily supporting member.
 7. The manufacturing method ofpress-molded article according to claim 1, wherein, in the press step,pressing force is applied to the material of the flat plate portionflowing into the thickened portion-forming section.
 8. The manufacturingmethod of press-molded article according to claim 1, wherein the memberto be pressed is molded by a hot press.
 9. A press molding apparatus formolding a member to be pressed including a flat plate portion,comprising: a first press portion opposing to a first end portion of theflat plate portion; a second press portion opposing to a second endportion of the flat plate portion, the second end portion being locatedon an opposite side of the first end portion; a first opposing surfaceopposing to a first main surface of the flat plate portion; a secondopposing surface opposing to a second main surface of the flat plateportion, the second main surface directing opposite to the first mainsurface; and a driving section for bringing the first press portion andthe second press portion closer to each other to press the flat plateportion, wherein: a thickened portion-forming section is formed on atleast one of the first opposing surface and the second opposing surfacefor forming a thick part on the flat plate portion by allowing a part ofa material of the flat plate portion to flow into the thickenedportion-forming section; the first opposing surface and the secondopposing surface, while facing to each other, keep in contact with theflat plate portion during pressing; and at least one of the firstopposing surface and the second opposing surface is moved to the pressdirection as the flat plate portion is pressed by the first pressportion and the second press portion.
 10. The press molding apparatusaccording to claim 9, wherein: the first press portion and the firstopposing surface are provided in a same die; and the second pressportion and the second opposing surface are provided in a same die. 11.The press molding apparatus according to claim 9, wherein: the dieprovided with the first opposing surface includes a first dividedportion and a second divided portion formed separately from the firstdivided portion; the first press portion is formed in the first dividedportion; and the second press portion is formed in the second dividedportion.
 12. The press molding apparatus according to claim 11, whereinthe first divided portion and the second divided portion have acomb-teeth shape so as to mesh with each other.
 13. The press moldingapparatus according to claim 9, wherein the first opposing surface andthe second opposing surface are arranged along a perpendiculardirection.
 14. The press molding apparatus according to claim 13,comprising a temporarily supporting member for supporting the flat plateportion to maintain positions of the first main surface and the secondmain surface along the perpendicular direction.
 15. The press moldingapparatus according to claim 9, comprising a back-pressure applicatorfor applying pressure force to the material of flat plate portionflowing into the thickened portion-forming section.